Pump plunger



Nov. 5, 1940. v. MANcUso PUMP PLUNGER Filed July 5, 1938 INVENTOR. Victor Mancuso T RNEY.

FIG. 2.

FICi'.

Patented Nov. 5, 1940 PUMP PLUNGER Victor Mancuso, Los Angeles, Calif., assignor to Axelson Manufacturing Co., Los. Angeles, Calif., a corporation of California Application July 5, 1,938, Serial No. 217,445

4 claims.

My invention relates to pump plungers and has particular reference to a plunger adapted for use in an oil well pump.

In the pumping of oil wells it is the common 5 practice to employ a reciprocating barrel and plunger type of pump submerged in the oil in the well, the plunger or other reciprocating part being connected by means of sucker' rods to power apparatus at the ground surface, while the barrel or stationary part of the pump is secured upon the lower end of a string of oil flow tubing extending to the ground surface. In such pumps it is the common practice to employ within the barrel a liner comprising generallya series of accurately machined tube sections disposed end to end to provide an accurately measured and close fitting barrel within which an elongated tubular plunger reciprocates. The liners are usually constructed of cast iron or relatively hard steel to resist wear, while the plungers are likewise usually formed of relatively hard material, or lpreferably they are provided with hardened exterior surfaces to resist wearof the plunger as it reciprocates within the barrel liner.

Such hardened surfaces may be formed either by case hardening the exterior of the plunger or by applying a coating or plating of hard material such as chromium about the exterior surface of the plunger. Thus the body of the plunger may be made of material selected for its toughness and tensile strength and the outer surface of the plunger may be so treated as to provide the necessary wear resistance without material sacrice of the toughness and tensile strength required for other functions of the plunger.

As will be understood by thse skilled in this art, the plungers are usually provided with working valves, preferably constructed as parts lseparate from the plungers and arranged to 'be cou- 40 pled to the plungers by male and female threaded connections. Such working valves may be located either at the top or at the bottom of the plungers. Also, couplings must be provided for coupling the sucker rods to the pump plungers which, like the working valves, must be connected to the plungers by male and female threaded connections. 'I'he plungers may also be provided with valve pullers, usually located at the bottom end of the plungers, and such pullers are also usually coupled tothe plungers by male and female threaded connections.

Heretofore it has been the common practice to form the plunger of a relatively thin-walled tube of suitable steel, formed with female threaded coupling members at either end of such tube. l

and to employ male threaded coupling members on the valves, sucker rod couplings, valve pullers,

l or other devices to be connected to the plunger.

When such male threaded attachments are inserted into the ends of the plunger and tightened 5 therein, the forces exerted between the threads of the attachments and the plunger tend to expand the ends 0f the plunger radially.

The forces exerted between the angular faces of the female threads in the plunger ends and 10 the male threads on the usual valves or other attachments are such as to tend to radially expand or swell out the plunger end. Since the plungers are designed to flt snugly within the liners of the barrel (only a sufficient clearance 15 being allowedy between them to permit the relative reciprocation of the parts and at the same time being close enough to seal off the luidcolumn), such expansion or swelling causes the plunger to fit too tightly and may result in one 20 or more of several undesirable eiects, namely:

(1) The too close fit between the plunger and the barrel of the pump may result in premature wear of the contacting surfaces, thus bringing about premature failure of the pump due to loss 26 of fluid-sealing ability.

(2) Such too close nt between the plunger and the barrel of the pump may result in the formation of scratches or cuts in the contacting surbe present and which frequently reach 4000 poundsor more per square inch, and the jet action of the uid through the cuts will cause fur- A ther uid cutting ofthe surfaces and failure of 35 the pump for this reason.

-(3) The too close ilt between the lplunger and the barrel of the pump may result in the galling of the contacting surfaces and the building up of the material of veither the plunger or the liners 40 so as to aggravate the swelling and tightness lof flt. Such swelling, if it does not result in the destruction of the contacting surfaces, rendering the pump unfit for furtherservice, may at least result in the plunger "sticking" in the barrel, 45 requiring the removal of the pump from the well (at considerable expense) to free up the plunger. Such building up" of the plunger diameter may also be sufdcient to so enlarge the plunger as to fproduce a wedging action between the 50 plunger'and the barrel or liner resulting` in the splitting of the barrel or liner.

Such swellingcannot be readily or accurately compensated for during the manufacture of the plungers by merely under-cutting" or reducing q,

the diameters of the. plunger ends, since the amount of swelling or expansion which will occur when the valves or other attachments are screwed up cannot be accurately predicted and the plunger ends will be either too tight, resulting in the opportunities for failure recited above or the plunger ends will be too loose which provides a space near the ends of the plungers into which sand or deposits of solid chemicals, such as gypsum or other solid materials precipitated from the well fluid, may accumulate and grow upon the plunger surface, resulting in an abrasive surface causing undue wear on the barrel or liners or such growth may be sufficiently great to enlarge the effective diameter of the plunger to such extent that a wedging action between the plunger and the liner or barrel takes place, causing-cracking or splitting of the liners or barrel.

It is therefore desirable that the ends of the plunger should so accurately t the accurately sized interior of the liner or barrel walls that the ends of the plunger will act to scrape sand or other solid particles oif of the liner walls upon each stroke of the pump and thus avoid building up of such solid deposits on the plunger walls.

Further, the major portion of the wear on the plungers in this type of pump occurs at the ends of the plunger. Any attempt to provide hardened surfaces, or to chromium plate or otherwise coat the surface of the plunger ends to resist this wear is defeated by the screwing up of the attachments resulting in this radialexpansion for the reason that this radial expansion places strains within the surface materials resulting in cracks therein and frequently small particles of the plunger material or coating material will break off and become lodged between the plunger and liners resulting in the scoring of the plunger and liners and galling of these parts.

It is therefore an object of my invention to provide a pump plunger with coupling members formed thereon, so arranged that tightening of attachments upon the plunger will not produce any forces tending to expand the plunger ends and thus permit the accurate machining of the plunger ends -to t accurately with the pump barrel or liner in proper sealing relationship.

Another object of my invention is to provide a pump plunger in which the walls at one or both ends of the plunger are thickened and in which one or both ends of the plunger are provided with male coupling elements to be received in female coupling members on sucker rod couplings, working valves, pullers, or other devices to be attached thereto so that any radial forces exerted by reason of the attachment of 'such devices will be exerted inwardly of the plunger instead of outwardly.

Another object of my invention is to provide a plunger which may have hardened surfaces or hardened surface materials applied thereto and in which forces exerted by the attachment to the plunger of valves, pullers, or other devices will not cause radial or annular expansion of the plunger which might result in the cracking of the surface or surface material.

Another object of my invention is to provide a plunger of the character set forth wherein thickened walls at one or both ends of the plung' er may be cut away for the reception of wear resistant rings separate from the body of the plunger and attached thereto.

Other objects and advantages of my invention Will be apparent from a study of lthe following specification, read in connection with the accompanying drawing, wherein Fig. 1 is a vertical sectional view taken through a typical oil well pump and illustrating the application of my invention thereto.

Fig. 2 is an enlarged detailed vertical section of one end of a plunger constructed in accordance with my invention.

Fig. 3 is an enlarged detailed vertical sectional view, similar to Fig. 2, but illustrating a modified form of plunger embodying the principles of my invention.

Referring to the drawing, I have illustrated in Fig. 1l a typical oil well pump as comprising a pump barrel I usually 'constructed as a thinwalled tubular jacket 2, the upper end of which is threaded as at 3 to receive a tube coupling collar l by which the barrel I may be stationarily secured at the lower end of a string of oil iiow tubing. The barrel I also includes a tubular liner 5 which may be constructed as illustrated herein of a plurality of short sections of liner disposed end to end along the length of the Jacket 2 and dei'lning with their interior surfaces an elongated, accurately machined cylinder in which reciprocates a pump plunger 6. The plunger 6 is illustrated as being formed of a suitable length of thin-walled tubular material, the external diameter of which is so formed as to snugly fit the internal diameter of the liner 5 so that as the plunger 8 reciprocates within the liner, little opportunity is aorded for leakage of cil between the plunger end and the liner. 'I'his type of pump plunger is known in the art as the close fitting type, by which is meant that the plungers are fitted accurately within an accurately sized bore so as to prevent fluid leakage between the plunger and the Walls of the bore without requiring the employment of piston rings, packing elements, cups or similar exible sealing members.

In the form of pump illustrated in Fig. 1 the upper end 1 of the plunger is secured to a working valve 8 which in turn is provided with a pin coupling member 9 to which the lower end of a string of sucker rods may be secured and by which the plunger may be reciprocated within the barrel I.

As hereinbeiore explained, the usual construction of the ends of the plunger of such pumps provides a female coupling member in the end of the plunger, but in accordance with my invention the upper end 1 of my plunger is swaged or upset to provide a relatively thick wall section as indicated at I at this end of the plunger so that the extreme upper end of the plunger may be reduced in diameter and provided with external threads, as indicated at II, to define a male coupling member I2 at the end of the plunger to be received in a female coupling member I3 formed upon the lower end of the working valve 8.

Working valves, one typical form oi. which is shown at 8, usually include a cage I4 having a plurality of oil flow openings or passages I formed therein, the `lower end of the cage I4 being provided with an internal recess I6 for the reception therein of a ball valve seat i1, the seat having an annular radially extending flange I8 abutting shoulders I9 formed at the upper end of the seat recess in the cage. The seat I1 is held in place within the cage, when assembled upon the pump plunger 6, by the engagement of the upper end surface 20 of the pump plunger coupling member I2 with the lower surface of the seat flange I8. A ball valve 2| is contained within the cage and is adapted to se'at upon the y i. 2,220,831 tvaiveseat n ariete nrt therefrom as the plunger 'isv raised vand lowered respectively.

the plunger may have -applied thereto afrelativelyvv thin coating or plating of hard material, such as chromium, which is particularly adapted not onlyto provide a hard, wear resistant surface, but also acts to prevent the attack by corrosive, contents of the oil upon the steel of the body of the plung- As shown in Fig. v2, the coating 22 extends not only along the longitudinal walls of the plunger but also, and preferably, extends about the shoulder 23 formed at the end of thev plunger by the reduction in diameter thereof to provide the,

male coupling member I2, the surface coating preferably terminating at the junction 24 of the shoulder with the projecting coupling end I2.

It will be apparent from the construction hereinbefore described that the attachment of the working valve 8 to the plunger will not exert any force upon the upper end of the plunger tending to expand this end of the plunger and placing no strains upon the coating 22 which would tend to crack such coating or, where the plunger is provided with a case hardened surface, this hardened portion of the plunger will not be subjected to expansive strains which would tend to crack the surface. Thus the valve 8 may be tightened upon the end of the plunger with such force as may be necessary to insure tight `engagement thereof with the plunger and to resist the shocks and strains to which such coupling would be subjected during the normal reclprocation of the plunger by the sucker rods, without fearv of breaking or cracking the hard and brittle surface materials of the plunger.- Moreover, since the radial forces exerted by tightening the fittings upon the plunger end are now exerted inwardly of the plunger, there will be no swelling of the plunger ends tending to alter the clearance which has been accurately allowed for in the manufacture of the plunger and liners. I

Where the standing valve is to be located upon the upper end of'the plunger the lower'fend 262of the plunger may be of conventional construction provided with female threaded coupling at its lower end for attachment to standing valve pullers or other devices to be located at the lower end of the plunger. However, I prefer to provide the lower end 25 with the same type of male coupling member as was described for the upper end of the plunger. This coupling member 26 may be formed by upsetting the material of the lower end of the plunger to provide thickened walls which will permit the extreme lower end to be formed of reduced diameter, as indicated at 21, to provide the externally threaded coupling member .26 to which a valve puller 2l or other device may be secured. The provision of the male threaded coupling member 28 at the'lower end of the plunger permits the valve puller 28 to be.

tightly fitted to the plunger without danger of cracking or breaking the coating or hard surfac.

ing of the plunger at this end while, as is illustrated in Fig. 1, the junction of the surfaces of the valve puller 28 and the exterior surface of the plunger may be made flush with each other.

Likewise, if desired, a working valve may be provided at the lower end ofthe plunger coupled thereto in the same mannei as was described for l the coupling of the puller.

By providing the male end onthe-'plunger and the female coupling members on the valves, pullers, or other devices to be attached to the plunger, it will be apparent that any expansionof any of the members, due to tightening one upon the other, will exert such expansive forces only upon the attachments, which are usually so designed as notto be damaged lby the forces encountered.

The provision of the upset end on the plunger 6 providing the `thickened walls thereat, also readily permits the employment of wear resistant rings or other inserts at the upper or lower or both ends ofthe plunger, as indicated particularly in Fig. 3. The upper end of the plunger d may be cut away to provide an annular recess 29 extending from the shoulder 23, and a ring l0 of hard steel or other hard wear resistant material may be shrunk upon the plunger and its'outer surface Il ground on flush with the outer surface of the body of the plunger C. Thus, the main body of the plunger may be formed of material selected for its toughness and tensile strength and the upper and lower'ends of the plunger. which are subjected to most of the wear during the ncrmal life of the pump, will be formed of hard wear resistant material capable of withstanding the wearing friction between the plunger and .the

pump liner. e

By forming the shoulder 21st the extreme upper and lower ends of the plunger, a relatively sharp corner is provided at the upper and lower end of the plunger which will assist in scraping sand or other abrasive material from the walls of the liner as the plunger is reciprocated and. as

wardly and downwardly to assist in performing -such scraping function. i

While I have shown and described the preferred embodiment of my invention, I do not desire plunger, means associated with said plunger for4 indicated in Fig. 2, such shoulder may .taper inproviding a relatively hard wear-resistant exf terior surface upon at least one end of said plunger, said plunger having a'reduced diameter male threaded coupling member formed upon and extending from at least one of its ends for reception within female coupling members of attachments to be secured to the end of said plunger, whereby the forces exerted between the coupling members on the plunger end and the attachments will be directed inwardly of -the plunger. l

2. An an oil well pump construction which employs 'an accurately sized .bore in the barrel of said pump, the combination therewith of an elongated thin walled. plunger body reciprocably mounted inA said bore and having a diameter i adapted to make a close fitting sealing ilt with said bore substantially throughout the length of the plunger, an exterior surface coating on said plunger of relatively brittle hard surfacing material to provide a wear-resistant surface extending` at least to one end of said plunger, said plunger having amale threaded coupling member extending from that end of said plunger for reception within female coupling members of attachments to be secured thereto, wherebythe forces exerted between the coupling members of said plunger and said attachments will be directed inwardly of the plunger and produce no expansive forces in said coating material.

3. In an oil Well pump construction which employsan accurately sized bore in the barrel of said pump, the combination therewith of an elongated tubular pump plunger reciprocably mounted in said bore and having a body portion of one diameter adapted to make a close fitting sealing t with said bore substantially throughout' the length of said plungerl body, a male threaded coupling member of reduced diameter upon one end of said plunger and extending beof the coupling member and body portion of said plunger, whereby radial forces exerted by the interengagement of the coupling members of said plunger and lsaid attachments will be directed inwardly of such. plunger and produce no expansive forces in said surface coating.

4. In an oil well pump construction which employs an accurately sized bore in the barrel of said pump, the combination therewith of an elongated tubular pump plunger reciprocably mounted in said bore and having a body portion of one diameter adapted to make a close fitting sealing fit with said bore substantially throughout the length of said plunger body, a. male threaded coupling member of reduced diameter upon one end of said plunger and extending beyond the body portion thereof for reception Within female threaded coupling members of attachments to be secured to said plunger, an annular recess formed in the body portion at the shoulder defined between the two diameters of the coup ling member and body portion of the plunger, and a wear-resistant ring extended about said plunger body and secured in said recess to form a wear-resistant part of said plunger body at said shoulder.

VICTOR MANCUSO. 

